This article describes the changes in the land cover and management of floodplains in towns located on Poland’s Oder River, estimates flood risk and how it has been changing in these towns, and how these changes have affected the environment. The paper also includes an analysis of trends in floodplain management defined in local planning documents. The research was conducted for the period of 1995-2010 and included two towns: Kostrzyn on the Oder and Krosno Odrzańskie. The former lies in the lower course of the Oder and the latter in its middle section. The research indicates that flood risk has risen due to the continuous development of urbanized areas (both unbuilt and built-up) that used to be exploited as arable land. That had a negative effect on the environment, as well.